SPINAL ACCESSORY NERVE. 



749 



dean region (la region hyoidienne superieure), 

 where it terminates. The external branch 

 passes downwards below the sterno-cleido- 

 mastoid muscle to reach the trapezius, in 

 which it is chiefly distributed.* 



Fig. 521. 



From Sendz, reduced one-half. 



A, part of cerebellum cut across ; B, medulla ob- 

 longata; c, spinal chord ; a, floor of fourth ventricule; 

 b, calamus scriptorius ; cc, posterior pyramidal 

 bodies ; d, right restiforme body obliquely divided 5 

 ff, lateral columns of spinal chord; hh, posterior 

 columns of spinal chord; i, posterior longitudinal 

 fissure; k k, posterior roots of spinal nerves; 33, 

 roots of vagus nerve ; 44, roots of glosso-pharyngeal ; 

 555, roots of nervus accessorius ; 6, ganglion of the 

 root of the vagus or superior ganglion ; 7, auricular 

 branch of vagus ; 8, right ganglion petrosum of 

 glosso-pharyngeal ; 9, ramus anastomicus of Jacob- 

 son ; 10, communicating branch between the superior 

 ganglion of the vagus and the ganglion petrosum ; 

 11, roots of the accessory which form its internal 

 branch ; 12, roots of the accessory which form its 

 external branch ; 13, glosso-pharyngeal nerve ; 14, 

 trunk of the vagus ; 15, pharyngeal branch of 

 vagus ; 16, filaments of this branch that come from 

 the vagus ; 17, filaments of this branch that come 

 from the internal branch of the accessory; 18, 

 ganglion of the trunk of the vagus or inferior 

 ganglion; 19, nervus laryngeus superior; 2222, 

 communicating branches between the ganglion of 

 the trunk of the vagus and the superior ganglion of 

 the sympathetic ; 23, fibres of the internal branch 

 of the accessory which do not enter into the for- 

 mation of the ganglion of the trunk of the vagus ; 

 24, branch from these fibres which joins itself to * 

 the external branch of the superior laryngeal nerve. 



Physiology of the accessory. The peculiar 

 origin and course of this nerve, and particularly 

 its intimate connection with the par vagum, 

 have formed the basis of most of the specula- 

 tions on its functions since the time of Willis. 

 It was maintained by Willis that this nerve, 

 from its connection with the par vagum, re- 

 gulates those involuntary movements of the 

 neck and arm caused by the emotions and 



* Recherches d' Anatomic Comparee sur le Chim- 

 panse" : par W. Vrolik, p. 40. Amsterdam, 1841. 



passions.* Lobstein likewise believed that 

 the spinal accessory joins the vagus for the 

 purpose of connecting itself with the in- 

 voluntary functions, and he supposed that 

 its paralysis might also affect the move- 

 ments of the pharynx and larynx.f Others 

 have maintained that it is a nerve of involun- 

 tary motion from the particular portion of the 

 spinal chord in which it is implanted. It is, 

 as is well known, one of Sir Charles Bell's 

 respiratory nerves, arising as he supposed from 

 a particular tract in the spinal chord to which 

 he gave the name of respiratory tract, and is 

 therefore, according to this view, a nerve of 

 involuntary motion. Bellingeri believes that 

 the lateral tract of the spinal chord, from which 

 the accessory arises, presides over the instinc- 

 tive and sympathetic movements, and that 

 it is consequently a nerve of involuntary 

 motion. J Arnold t Scarpa || , BischofF ^[, 

 Valentin **, and Longet f f , have maintained 

 that the accessory stands in the same rela- 

 tion to the vagus as the anterior roots of the 

 spinal nerves do to the posterior roots. JJ Ac- 

 cording to this last view, the vagus does not 

 originally possess any motor filaments, but 

 derives them from the spinal accessory. The 

 two first of these authors came to this con- 

 clusion on anatomical grounds alone ; the three 

 latter, from experiments upon these nerves in 

 living animals, as well as from their anatomy. 

 Bernard has arrived at the conclusion that it 

 is entirely a motor nerve, and that it enables 

 the larynx and pharynx, and muscles of the 

 neck in which it is distributed, to partake in 

 the production of the phenomena of phona- 

 tion, but that it does not assist in any of the 

 true respiratory movements.^ Dr. Todd and 

 Mr. Bowman ||||, on the other hand, believe 

 that the internal branch of the accessory is 

 composed of afferent nerves, and that the 

 mode of implantation of this nerve in the cen- 

 tral organs of the nervous system serves to 

 bring the sentient surface of the lungs and air- 

 passages into immediate relations with the 

 roots of all those nerves which animate the 

 great muscles of respiration, the phrenic, the 

 external thoracic, the cervical plexus, and the 

 motor fibres of the spinal accessory and vagus 

 nerves. 



All experimenters agree that the external 



* Opus cit. caput xxviii. 



t Ibid. pp. 345, 346. 



J Ibid. pp. 89, 90. 



Der Kopftheil des vegativen Nervensy stems. 

 Heidelberg, 1831. 



|| De Gangliis Nerv. deque Essen tia Nervi Inter- 

 cost. Ann. Univers. di Medicina, 1831. 



^ Nervi Accessorii Willisii Anatomia et Phy- 

 siologia, 1832. 



** De Functionibus Nervorum Cerebralium et 

 Nervi Sympathici, 1839. 



ft Anatomic et Physiologic du Systeme Nerveux, 

 &c., torn, ii., 1842. 



JJ It appears that this idea had been previously 

 suggested by Gb'rres (Exposition der Physiologic, 

 Coblentz, 1805, as quoted by Miiller). 



Archives Generates de Medecine, 4ieme serie, 

 torn. iv. and torn, v., 1844. 



|||| The Physiological Anatomy and Physiology 

 of Man, vol. ii. p. 130. 



